Abstract 4873: IKKα Bridges Central Tolerance to Innate Immunity and Inflammation

Abstract IKKα has emerged as a tumor suppressor in squamous cell carcinomas (SCCs) of skin, head and neck, and lung. Our recent studies indicate that inflammation is involved in lung SCCs in kinase-dead knock-in IkkαKA/KA mice. However, how IKKα prevents inflammation has not been fully understood yet. In the present studies, we showed that IkkαKA/KA mice developed reduced thymic medullary regions, systemic inflammation, and severe skin damage, indicating that IKKα plays an essential role linking central tolerance to innate immunity and inflammation. In line with previous studies of the role of NF-κB pathway in thymic medulla formation and the establishment of central tolerance, we found that NF-κB pathway was inactivated in the presence of kinase inactive form of IKKα in thymic epithelial cells. Depleting the lymphocytes, thymus, T cells, macrophages, and/or reintroducing transgenic IKKα into the skin or thymus rescued the severe skin phenotypes. Transferring IkkαKA/KA T cells, but not wild-type T cells, reconstituted the severe skin phenotypes and SCCs in the lungs and forestomach of IkkαKA/KA/Rag-/- mice. We found that the self-reactive T cells provided TGFβ signaling, which enhanced the expression of monocyte chemoattractant protein-1 (MCP-1) in keratinocytes. As a result, increased level of MCP-1 led to robust recruitment of macrophages to the skin, resulting in skin inflammation and hyperproliferation. This study reveals an important IKKα/TGFβ/MCP-1 signaling axis that orchestrates central tolerance and inflammation in the maintenance of tissue homeostasis. Citation Format: Feng Zhu, Zhisong Chen, Jami Willette-Brown, Dakshayani Lomada, Sean R. Davis, Timothy Back, Teizo Yoshimura, Zhonghe Sun, Xiaolin Wu, Robert Wiltrout, Ellen Richie, Ulrich Siebenlist, Giorgio Trichieri, Yinling Hu. IKKα bridges central tolerance to innate immunity and inflammation. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4873. doi:10.1158/1538-7445.AM2014-4873